In order to simplify the assembly and disassembly of a timepiece including a case enclosing a movement, the patent document CH-A-554 560 (GB-A-1.370.528) proposed a construction wherein the crystal and the back cover making up the constituent parts of the case are assembled with a single common caseband into which they are driven with the interposition of a packing between the section of each of them and said caseband which assures on the one hand a moisture tight seal and on the other hand maintaining in place of these parts, the interior surface of the caseband in which the crystal and the back cover are engaged being cylindrical and having no support shoulder.
In order to arrive at this result, the cited construction employs, in addition to the mentioned fittings two additional rings and a distancing sleeve forming a casing ring and separating said fittings, thus a plurality of parts manufactured independently from one another which it is necessary to stack onto one another when one proceeds with assembly of the case. This leads to a multiplicity of relatively expensive tools which increase the final cost of the case as is also increased the time required for assembly. One will also note for this assembly the use of two relatively complicated jigs which must be specifically adapted to the case which is to be assembled.
The patent document DE-A-34 21 168 describes a tubular fitting including a projection reducing its internal diameter. However, in this construction, the caseband does not include a continuous cylindrical internal wall since a shoulder is provided in the lower part of the caseband on which the fitting is supported. This arrangement complicates the rapid assembly or disassembly of the watch and above all the manner of obtaining the caseband, the internal wall of which is not continuous.